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RESEARCH ETHICS By Kristie Sullivan, M.P.H., and Nancy Beck, Ph.D.

TOXICITY TESTING

Rabbit-Free Skin Irritation Test Adopted WorldwideAfter more than a decade of scientific research, the Organisation for Economic Cooperation and Development (OECD) has approved a new, nonanimal testing guideline for skin irritation that can almost completely replace the Draize rabbit skin test.

The Draize, developed in the 1940s, has been the traditional way to assess whether chemicals, pesticides, cosmetics, and consumer products might irritate human skin. The test involves applying substances to shaved skin on rabbits’ backs. The new guideline allows for the use of three artificial human skin models engineered by SkinEthic in Nice, France, and MatTek of Ashland, Mass., or other methods that meet the guideline’s specifications.

These new methods provide a humane—and more accurate—assessment of the potential for human skin irritation. Manufacturers construct a 3-D layer of skin using excess skin cells from surgical procedures; the models closely mimic the properties of human skin. Substances are applied to the model to assess the potential for skin damage.

The OECD produces safety-testing guidelines for its 31 member nations, which include North America, Western Europe, Japan, South Korea, Australia, and other large economies, as well as many affiliated countries that also abide by the test guidelines, such as Brazil, Russia, and India.

Advances in Inhalation Toxicity TestingResearchers in the United States and Switzerland have created two new nonanimal models for assessing the dangers of inhaled toxicants.

Harvard researchers have invented a “lung on a chip” that shows great promise for testing human health effects of toxicants without using animals.

The Harvard model uses microfluidic technology—tiny chambers of cells separated by a membrane—to mimic lung construction. A vacuum on either side of the cells helps mimic expansion and contraction during normal breathing. The cells in the upper chamber are exposed to air and test substances, while lower chamber cells are bathed in fluid that mimics the internal side of the lung barrier.

The model can test, for example, whether inhaled nanoparticles can cross this barrier, or whether inhaled substances cause the cells to produce allergic or other harmful reactions. Microtechnology can allow many substances to be tested at once, producing faster results.

Switzerland-based Epithelix created the MucilAirTM model to assess the effects of repeated exposures to airborne chemicals on human airway cells. MucilAirTM is a 3-D construct of human cells from the respiratory system.

When “grown” in a plastic dish, the model differentiates into the various cell types of the respiratory system, including goblet, basal, mucus, and ciliated cells. The cells even contain CYP450 metabolic enzymes–crucial for understanding the potential toxic effects of inhaled substances. Most important, the model can be used for up to a year, enabling longer-term tests than other in vitro models.

At the recent Linz Congress on Alternatives to Animal Testing, Epithelix scientists presented the results of tests conducted with formaldehyde on the MucilAirTM model. The data strongly correlate with what is known about human responses to formaldehyde. The company plans to expand the model to allow testing for allergenicity and carcinogenicity.

Physical Inactivity Does Not Cause Weight Gain in Children
Lack of physical activity is not the cause of weight gain in children, according to a study in Archives of Diseases in Childhood. Researchers measured physical activity and body fat percentage in 202 children annually from age 7 to age 10. The amount of physical activity did not result in changes in body fat. Although physical activity is important, focusing on food intake may have a larger impact on weight loss, the researchers concluded.

Meat Causes Weight GainEating meat leads to weight gain, according to a new study published in the American Journal of Clinical Nutrition. Researchers studied the diets of 373,803 participants in the European Prospective Investigation into Cancer (EPIC) study. Those who ate 8.8 ounces (about two servings) of meat per day gained more weight year by year, compared with people who ate less meat or none at all. The weight gain attributable to meat consumption was about 1 extra pound per year. The researchers concluded that reducing meat consumption may help people avoid weight gain.

Higher Meat Intake Leads to Earlier Puberty for Girls
According to a new study, girls who eat the most meat products during childhood may have an earlier occurrence of puberty, increasing their risk of diseases such as cancer, heart disease, and osteoporosis. Researchers followed 3,298 girls in Bristol, England, and gathered their dietary intakes when they were 3, 7, and 10 years old. Forty-nine percent of girls who ate more than 12 portions of meat per week started their periods by age 12, compared with 35 percent of girls who ate fewer than four portions of meat per week.

Rogers IS, Northstone K, Dunger DB, Cooper AR, Ness AR, Emmett PM. Diet throughout childhood and age at menarche in a contemporary cohort of British girls. Public Health Nutr. Published ahead of print June 8, 2010.

MENTAL HEALTH

Meaty Diets May Fuel Depression
Vegetarians have lower instances of depression, according to a new study in Nutrition Journal. Researchers looked at 60 vegetarians and 78 meat-eaters in the southwestern United States and found that vegetarians scored significantly better on standardized mood tests. The mood tests measured depression, anxiety, and stress and were compared against food frequency questionnaires. The vegetarians consumed less eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid—all animal sources of essential fatty acids—but reported higher mean intakes of plant sources of omega-6 and omega-3.